Question

Решите уравнение: 1) 3x(x- 7) - x(4 + 3x) = 5; 2) 5x- x2 +3 = x(2 - x); 3) x(4x+1) - 7(x2 - 2x) = 3x(8 - x) + 6

Answer 1

Ответ:

1) 3x(x-7)-x(4+3x) = 3x²-21x-(4x+3x²) = 3x²-21x-4x -3x² = -25x

-25x = 5

x = 5/(-25) = -1/5

2) 5x-x²+3 = x(2-x)

5x-x²+3-2x+x² = 0

3x+3 = 0

3x = -3

x = -1

3) x(4x+1)-7(x²-2x) = 3x(8-x)+6

4x²+x-7x²+14x = 24x-3x²+6

-3x²+15x-24x+3x²-6 = 0

-9x-6 = 0

-9x = -6

x = 6/9 = 2/3